Term
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Definition
| voltage difference between 2 parts |
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Term
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Definition
| outside and inside of cell have a different net charge |
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Term
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Definition
| potential becomes less negative than resting potential |
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Term
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Definition
| when membrane that has been depolarized returns toward resting value |
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Term
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Definition
| when potential is more negative than resting levels |
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Term
| What kinds of cells have membrane potentials? |
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Definition
| Electrogenic pumps create concentration gradients and thus membrane potentials (nerve cells have membrane potentials) |
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Term
| Two gating mechanisms which alter the permeability of neural and muscle membranes to specific ions? |
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Definition
Mechanically gated channels: membrane ion channel that is opened or closed by deformation or stretch of the plasma membrane.
Voltage gated channels: cell membrane ion channel opened or closed by changes in the membrane potential |
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Term
| Permeability of cell sodium, potassium, and chloride |
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Definition
| Sodium is .04, potassium is 1, chloride is .04 |
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Term
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Definition
| electrical signal propagated by nerve and muscle cells |
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Term
| How is ATP generated and what determines its size? |
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Definition
An all-or-none depolarization of membrane polarity and has a threshold refractory period and is conducted without decrement.
Changes in membrane permeability allow sodium and potassium to move down concentration gradient. Begins with a depolarizing stimulus, which opens some voltage gated sodium channels and further entry of more sodium ends to depolarization. |
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Term
| Repolarization of a neuron occur |
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Definition
| Sodium permeability aburptly declines because cycle of positive feedback is broken by blocking sodium channels. Depolarized state opens voltage gated potassium channels. Potassium flux out of cell rapidly repolarizes membrane to resting value. |
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Term
| Cell's equilibrium potential |
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Definition
| voltage difference across a membrane that produces a flux of a given ion species that is equal but opposite to the flux due to the concentration gradient of the same ion species. |
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Term
| Absolute refractory period |
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Definition
| time during which an excitable membrane cannot generate an action potential in response to any stiumlus (sodium channel is already open or proceeded to inactivated) |
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Term
| Relative refractory period |
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Definition
| time during which excitable membrane will produce action potential but only to a stimulus of great strength than usual threshold strength |
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Term
| How does a threshold stiumulus change as the relative refractory period progresses |
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Definition
| Stimulus has to be greater than usual but as relative refractory period goes on, it doesnt have to be as great |
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Term
| What ion channel changes are responsible for the changes in threshold stimulus |
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Definition
| Voltage gated sodium channels: some have returned to resting state potassium channels are open |
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Term
| What portion of the neuron are voltage gated ion channels found |
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Definition
| There are none on dendrites, some on soma, lots on axons |
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Term
| What portions of the neuron are transmitter gated ion channels found |
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Definition
| any portion where receptor is present |
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